Bokura,
I'm going to be honest here. I honestly can't believe you are still alive taking that much Xanax. You, my friend, are a walking miracle in that respect. You cannot go on doing this and not lose your life. You have to take action TODAY! Go to your parents and tell them you need help and have them help you get to a doctor ASAP. I really think you should go to the ER! I'm 3+ years clean from an addiction to Xanax and I overdosed 3 times, the last time I was put on life support for a short time. I was taking 1/4 of what you are taking. At the most 10mg. Everyone is different in their tolerance, but you're playing with fire BIG TIME! Add on to your miracle that you haven't suffered a grand mal seizure during these withdrawal periods you talked about.
There are low cost and no cost rehab options through the Salvation Army and any hospital could help you set that up, I believe. I'm terrified for you. You're so young, and I know you feel invincible, but this is going to take your life...it's just a matter of time. Get help!!!! I'll be praying for you and please PM me if I can help you in any way.